Children in America's inner cities are exposed to multiple known and potential neurodevelopmental toxicants, including pesticides, PCBs and lead. Organophosphate pesticides, such as chlorpyrifos, are of special concern. They are applied widely, and their use appears to be increasing. Recent animal data, not yet confirmed in humans, suggest that chlorpyrifos at relatively low levels of exposure can impair neuronal development in the fetal brain. To explore the neurodevelopmental impact of current exposures to environmental toxicants in the inner city, we propose to undertake a five-year prospective epidemiologic study in a ethnically diverse birth cohort. of New York City children. Our primary objective is to determine whether pre- and post-natal exposures to environmental toxicants are associated with delayed mental and psychomotor development. We plan to follow 300 nulliparous mothers and their newborn children delivered at the Mount Sinai Hospital (150 African-Americans and 150 Hispanics). The mothers will be enrolled during the prenatal period and the infants will be evaluated at birth, 1 year and 2 years of age. To assess environmental exposures, biological specimens will be obtained including maternal serum, maternal urine, cord blood, and infant urine. Questionnaires that will assess indoor pesticide use, residential history, dietary intake, especially fish consumption, as well as other relevant characteristics will be administered to the mothers during the prenatal as well as the postnatal follow-up assessments. A subsample of 100 homes in East Harlem will be visited, and house and carpet dust, as well as "hand wipe" samples and wipe samples of toys will be assessed for chlorpyrifos levels during the prenatal period and again during year 2 and 5 of this project. This subsample will serve as an external comparison or control group to the intervention group being followed in Project 1. Evaluation of infants and children will utilize the Brazelton Neonatal Behavioral Assessment Scale at birth and the Bayley Scales of Infant Development at ages 1 and 2 years. The unique contribution of this study is that it will assess the effects on childhood growth and neuro-development of current multiple potential exposures to developmental toxicants among inner-city, minority children. Decrements in early development can lead to lifelong neurodevelopmental and behavioral impairments.